Hey Draco,
I saw you up at NED in Oct last year, I will be back this year and with N2O on my bike. In the graph that you provided do you have the data and if so what the weight change in the bottle was over that interval. I will tell you something that I have done in the past to cheat the system a little bit. I have overfilled my bottles ( I have a 79 camaro I run a 300hp shot in and other cars ). I run usually 10 lb bottles both in my car and at work (yes at work), including the weight of the bottle full is 24lbs, I have had them weight as much as 27 - 28 lbs to keep a more consistant pressure for a greater period by slowly increasing bottle temp over the period of use (we could discuss ways to do this on a bike if we wanted). If you are running a 2lb bottle and observing that pressure drop I would like to see the data if you squeeze 2.5 lbs into it and maintain the same pressure. Just some food for thought and to add to the conversation. Hopefully I'll see you up there soon,
"O"